How to add the usb_host module on Raspberry Pi Pico 2 W?

[MarcelloTheArcane]

Is it possible to add the usb_host module on the Raspberry Pi Pico 2 W (RP2350)?

The Pico 2 is supposed to have USB host support in hardware, but when I try to import the module I get an error:

>>> import usb_host
Traceback (most recent call last):
  File "<stdin>", line 7, in <module>
  File "<string>", line 1, in <module>
ImportError: no module named 'usb_host'
Exception occured

>>>

Presumably it is possible, since other RP2350-based boards are listed under the "Available on these boards" section. Is there a setting somewhere, and will I need to build the .uf2 file from source?

---

To make sure I'm not after the wrong thing, I am trying to make a Raspberry Pi Pico 2 W with a USB port wired to two GPIO pins, that can read a USB keyboard input and make a web request. I assume this is the right module to use here?

[Lobo-T]

Are you the victim of some AI hallucination or something?
I don't think there is USB host support for the RP2, yet.

Yes, the RP2350 can act as USB host, but it's not implemented in Micropython. And even in the C SDK it's only available on the actual USB port, not on any GPIO pins. Although a PIO USB implementation exists (https://github.com/sekigon-gonnoc/Pico-PIO-USB), it's not available through Micropython.

[MarcelloTheArcane]

No, I think it was just a human hallucination: I must have opened the Circuitpython page (which comes up when you Google "micropython USB host") by mistake!

[ladyada]

you might be thinking of Circuitpython which does have usb host for RP2350 https://learn.adafruit.com/using-a-keyboard-with-usb-host/circuitpython

[MarcelloTheArcane]

Thank you, it looks like I was mistaken. I actually have the project coded using Circuitpython, but I was looking to change to Micropython so I could have the USB polling in a separate thread.

It's a barcode scanner acting as HID keyboard, which submits a web request when you scan a code. Since the web request is blocking, the USB host stops polling, which drops the next scan if it happens too quickly.

It looks like I'll have to try to translate the code to C instead, which is daunting!

[mattytrentini]

@andrewleech has been working on USB Host for MicroPython, I'm sure he could do with an additional tester!

[andrewleech]

@MarcelloTheArcane yes I have been working on USB host support for micropython!

rp2 is one of the tested configurations too, using the PIO based driver.

It's still needing cleanup before ready for official PR but I've put up a draft here if you want to take a look: andrewleech#7

[MarcelloTheArcane]

@andrewleech Thanks for the offer! I'm happy to help where I can. Having said that, I'm a complete beginner to all this, and have no experience with building MicroPython...

I've tried cloning your repository and running the following in the machine-usbhost branch, but I'm getting an error:

$ which picotool
/usr/local/bin/picotool
$ make BOARD=RPI_PICO2_USBHOST V=1 submodules
make -f ../../py/mkrules.mk GIT_SUBMODULES="lib/pico-sdk" submodules
make[1]: Entering directory '<directory>/ports/rp2'
Updating submodules: lib/pico-sdk
cd ../.. && git submodule sync lib/pico-sdk
Synchronizing submodule url for 'lib/pico-sdk'
cd ../.. && git submodule update --init --filter=blob:none lib/pico-sdk 2>/dev/null || \
  git submodule update --init lib/pico-sdk
make[1]: Leaving directory '<directory>/ports/rp2'
cmake -S . -B build-RPI_PICO2_USBHOST/submodules -DUPDATE_SUBMODULES=1 -DMICROPY_BOARD=RPI_PICO2_USBHOST -DMICROPY_BOARD_DIR="<directory>/ports/rp2/boards/RPI_PICO2_USBHOST"
PICO_SDK_PATH is <directory>/lib/pico-sdk
Target board (PICO_BOARD) is 'pico2'.
Using board configuration from <directory>/lib/pico-sdk/src/boards/include/boards/pico2.h
Pico Platform (PICO_PLATFORM) is 'rp2350-arm-s'.
Build type is MinSizeRel
TinyUSB available at <directory>/lib/tinyusb/src/portable/raspberrypi/rp2040; enabling build support for USB.
BTstack available at <directory>/lib/btstack
lwIP available at <directory>/lib/lwip
Found User C Module(s): 
Updating submodules: lib/mbedtls lib/tinyusb lib/micropython-lib
Synchronizing submodule url for 'lib/mbedtls'
Synchronizing submodule url for 'lib/micropython-lib'
Synchronizing submodule url for 'lib/tinyusb'
-- Configuring done (4.6s)
CMake Error in CMakeLists.txt:
  IMPORTED_LOCATION not set for imported target "picotool" configuration
  "MinSizeRel".


CMake Error in CMakeLists.txt:
  IMPORTED_LOCATION not set for imported target "picotool" configuration
  "MinSizeRel".


CMake Error in <directory>/lib/pico-sdk/src/rp2350/boot_stage2/CMakeLists.txt:
  IMPORTED_LOCATION not set for imported target "picotool" configuration
  "MinSizeRel".


-- Generating done (0.2s)
CMake Generate step failed.  Build files cannot be regenerated correctly.
make: *** [Makefile:80: submodules] Error 1

I'm not too sure what I'm missing here, I can build for other boards (i.e. make BOARD=RPI_PICO2_W submodules) with no error.